Every year, tens of thousands of whales, birds, seals, and turtles die from contact with ocean-borne plastic bags. The animals may mistake the bags for food, such as jellyfish, or simply become entangled. Plastic bags can take up to 1,000 years to break down, so even when an animal dies and decays after ingesting a bag, the plastic re-enters the environment, posing a continuing threat to wildlife. While most plastic bags eventually break down into tiny particles, smaller sea creatures may still eat the sand-sized fragments and concentrate toxic chemicals in their bodies.